Gasification of hydrocarboncontaining oils



F. J. DENT 'ETAL 3,178,272

GASIFICATION OF HYDROCARB-ON-CONTAINING OILS 2 Sheets-Sheet 1 April 13, 1965 Filed Sept. 2 5. 1959 April 13 1965 F. J. DENT ETAL 3,178,272

GASIFICATION OF HYDROCARBON-CONTAINING OILS United States lPatent Office 3,378,272 Patented pr. 13, 1965 3,178,272 GASHICA'HON 0F HYDRCARBN- CNTAMG @ELS Frederick .llames Dent and Frank Chiltern Wood, Solihull, England, assigner-s to The Gas Council, London, England Filed Sept. 25, 1950, Ser. No. 842,251 Claims priority, application Great Britain, Dec. '7, 1954, 35,466/ S4 1 Claim. (Cl. 48--213) This application is a continuation-in-part of application Serial No. 551,144, tiled on December 5, 1955, and now abandoned.

This invention relates to the gasification of hydrocarbon materials which are liquid at temperatures ranging from ordinary temperatures to 500 C. and consist wholly or mainly of hydrocarbons including aliphatic hydrocarbons, for example, liquid or fusible bitumens, such as an oil or tar obtained by the distillation of coal, petroleum oil or a liquid or fusible fraction obtained therefrom.

An object of this invention is to gasify such hydrocarbon-containing oils by a hydrogenation treatment, which involves the splitting and hydrogenation of hydrocarbons, to produce gases which contain gaseous hydrocarbons consisting of methane with or Without other gaseous hydrocarbons, such as ethane. A further object is to produce from the hydrocarbon-containing gases, hydrogen-containing gases consisting mainly of hydrogen or of hydrogen and carbon monoxide.

In the process for gasifying a hydrocarbon-containing oil, in accordance with this invention, the oil is subjected to interaction With hydrogen to produce a gas containing gaseous hydrocarbons by passing the oil and a gas comprising hydrogen under a pressure within the range of 20 to 50 atmospheres through a bed of non-catalytic particulate solid maintained in the uidised state by the gas and having a temperature Within the range of about 700 C. to 800 C.

Under .these conditions of temperature and pressure the relatively reactive, that is to say the aliphatic constituents of which the oil may be Wholly or partly cornposed, are converted into gaseous hydrocarbons, principally methane. It has been found that the less reactive constituents that may be present in hydrocarbon oils, and are not converted into gaseous hydrocarbons under the aforesaid conditions can be so converted in a bed of a uidised non-catalytic particulate solid at temperatures above 800 C. and not exceeding about 900 C. under pressures within the range of 20 to 50 atmospheres or at temperatures above about 900 C. and not exceeding 1100 C. under pressures higher than 50 atmospheres, for example, up to or exceeding 200 atmospheres.

There may be used as the hydrogenating gas, for example, a mixture of carbon monoxide and hydrogen, such as water gas, produced by the gasification of solid carbonaceous fuel with steam. It may be of advantage to increase the hydrogen content of such a mixture by reacting a part or the whole of the carbon monoxide contained therein with steam in accordance with the known Water gas switch reaction, and subequently removing the carbon dioxide formed.

There may also be used a gas containing gaseous hydrocarbons, in addition to hydrogen, and the hydrogen content of such a gas may be increased by known methods to convert a part or the whole of the hydrocarbons into hydrogen and carbon monoxide, for example, by reacting the hydrocarbons with steam or oxygen or with both steam and oxygen. The oxygen may be used in the form of air, but it is preferable to use it undiluted or mixed with air. It desired, a part or the whole of the carbon monoxide so formed may be reacted with steam as described above, in order still further to increase the hydrogen content of the gas.

Instead of deriving the hydrogenating gas from a separate source, it may be obtained by treating a part of the hydrocarbon-containing gas produced to convert a part or the whole of the hydrocarbons therein into hydrogen. Such conversion of hydrocarbons includes conversion as described above into hydrogen and carbon monoxide with or without subsequent reaction of a part or the whole of the carbon monoxide so formed with steam to produce further hydrogen.

The non-catalytic particulate solid of which the uidised bed is composed may be, for example, a siliceous material or carbon, for example, coke dust, and it may include particles of carbon deposited during the reaction between the oil and the hydrogen.

rThe hydrogenation may be carried out in a single uidised bed or in a plurality of uidised beds at different temperatures. A plurality of fluidised beds may be used for the treatment of a composite oil containing two or more fractions of different reactivities, by introducing the composite oil into a bed operated under conditions suitable for hydrogenating substantially only the most easily reactive fraction, that is to say, at a temperature within the range of about 700 C. to 800 C. under a pressure of 20 to 50 atmospheres. The remaining fraction or fractions are then separated from the resulting gas and treated in a bed or beds operated under the appropriate conditions, that is to say at a temperature above 800 C. and not exceeding about 900 C. under 20 to 50 atmospheres, or at a temperature above about 900 C. and not exceeding 1l00 C. When more than one fraction remains after the first treatment, they may be supplied in admixture to a succession of separate beds operated under conditions of successively increasing severity to hydrogenate the several fractions in turn in the order of decreasing reactivity. Alternatively, when several fractions remain after the iirst treatment, they may be separated from one another and treated separately in beds operated under conditions suitable for the respective fractions.

If it is attempted to hydrogenate the whole of a composite oil in a single bed at the higher temperature required for the less reactive constituents, the diiiiculty often arises that only the more reactive constituents undergo hydrogenation, while the less reactive constituents undergo decomposition without hydrogenation, thereby being wasted and leading to the deposition of carbonaceous solids.

The several uidised beds may be separately supplied with hydrogenating gas, or the hydrogenating gas may be passed in succession through a series of iluidised beds. Thus, for example, a series of two or three beds may be operated at progressively decreasing temperatures in the direction of flow of the gas from one bed to the next, the hydrogenating gas being introduced into the rst bed. A composite oil containing two fractions, one more reactive than the other, may be introduced into the second bed in which substantially only the more reactive fraction iS hydrogenated. The less reactive fraction, which is carried away with the gases leaving the second bed, is separated by condensation from the gases and introduced into the first bed, which is operated at a higher temperature and concentration of hydrogen appropriate for hydrogenating the less reactive fraction. If a third bed is used, a light hydrocarbon oil, which is more readily hydrogenated than the fraction hydrogenated in the second bed, may be hydrogenated in the third bed by means of the residual hydrogen in the gases from the second bed. Alternatively, a third bed may be used for slightly coolsnc/sare ing the gases from the second bed, for example, to

The oil should be as far as possible in the form of vapour- -in- Athe iiuidisedY bed "in which itis treated. For Athis. purpose the oil may be introduced directly into the iluidised bed, but is preferably injected into the fresh hot hydrogenating gas passing toa uidise'd bed or into a hot fhydrogen-containing gas passing from Voney uidisedI bed toanother In the case of oils which can be completely `vaporised, they are preferably introduced as vapour into .the hydrogenating gas. In the case of yoils which contain .constituents that undergo thermalA decomposition `to form carbon orsolid carbonaceous products -at the temperature -fto which the oil must be heated, it may be `undesirable to introduce such oils directly into Ya tluidisedbed, as such "solid products may cause agglomeration of the luidi'sed .particles lMoreover, when such oils are introduced into Aa hydrogen-containing gas being supplied to a fluidised ,bed,-suchvdeeompos`ition "products may be deposited in and block the gas conduit.

In order to overcome this difficulty it is of advantage to -inject theoilinto a stream of solid particles suspended Yin and being carried along vwith the hot gas being supplied to 'a uidised bed. In this manner any solid decomposition rproductsformed-When the oil is injected into the hot gas are carriedalong with the suspended particles'and the gas, and are distributed in the uidised bed in an'in'nocuous-manner. The suspended particles for this purpose are vadvantageously derived from the iluidised bed by causing .a-part of the particles to ow under gravity in uidised -condition from the bed into an upwardly tlowing stream .of the hydrogenating gas passing into the bed, so 'thatthe -said particles become suspended in and carried along -With-the gaseous stream. The particles so entering the :gaseous stream being at a `high temperature assist in vaporising the oil injected 'into -the gaseous stream, in addition to carrying away decomposition products as described above.

`Since 'the hydrogenation reaction is exotherrnic the temperature required can usually be maintained by suit- -ably adjusting the temperature to which the hydrogenating -gas is preheated. If desired, additional heat may be sup- .plied by heat exchange between the hot hydrocarbonycontaining gas produced and the oil and/or hydrogenating gas. Additional heat can also be supplied, if neces,- sary, by introducing oxygen separately or together with ,the hydrogenating gas.

In order to produce a gas-containing hydrogen, forexample, atleast 50 percent of hydrogen, a gascontaining :gaseous hydrocarbons is produced by the process de- Y scribed above, and the resulting gas istreated as described .above t'o convert hydrocarbons into'hydrog'en, that is to say, iirst into hydrogen and carbon monoxide, followed, if desired, by the conversion 'of carbon monoxide by reaction With steam into hydrogen andcarbon dioxide and the removal of carbon dioxide part of the hydrogen-containing gas so obtained is Withdrawn as the product gas and the remainder, if'desired, after converting carbon monoxide, when present, into hydrogen and carbon dioxide and removing the latter, is used `for hydrogenating the oil.

In carrying out this process an oil containing more reactive yand less reactive constituents, for example a crude petroleumV oil, may be treated at a high pressure of, say, 30 atmospheres in a series of two or three beds in a single vessel as described above. The crude oil is injected into the second bed, and the unreacted tar is separated from the hydrocarbon-containing gas produced and injected for hydrogenation into the first bed in which the temperature and the concentration of hydrogen are higher than in the second bed. The third bed, if used, may serve ltor hydrogenating alight distillate or for cooling as described above. In order to convert gaseous hydrocarbons present in the gas into hydrogen and carbon monoxide, the gas is mixed with steam, and the mixture subjected under about atmospheres pressure to theaction of a suitable catalyst at SOO-900 C., the catalyst vessel being externally heated. The resulting gas may then be subjected to the water gas switch reaction in a separate vessel at about 300 C. A part of the hydrogen-rich'gas so obtained is withdrawn as product gas, and anotherpart` is compressed to 3'() atmospheres and used as the hydrogenating gas, after removing the carbon dioxide at any desired stage.

Instead of expanding the hydrocarbon-containing gas, it may bereactedfwith oxygen or oxygen' and steam at 30 atmospheres pressure. The resulting gas is then treated as described above, but at the same pressure and without the need of yexternal heating, 'to convert carbon monoxide by reaction with steam into hydrogen and carbon dioxide. f A* v In orderto produce a heating gas, for; example, town gas, rich in gaseous hydrocarbons, mainly'rnethane, a

hydrocarbon oil for example, petroleum oil, containingk 'more reactive constituents and less reactive,`for exranriple,

'aromatic, constituents, is/treated as described above in a uidised'bed to hydrogenate onlythe'r'n'ore reactiveconlstituents and yield a gas rich in gaseoushyd'rocarbon, having, for example, a hydrocarbon Acontent ofKA atleast 40 percenthe unreacted constituents are'separated'from the resulting gas and hydrogenated in a separate uidised bed to yield a 'gaspoorer in gaseous hydrocarboma part of ithe hydrocarbon-rich gas is'treated asdescribed above to convert hydrocarbon into hydrogen, the'resulting hydrogen-containing gans is used as the'hydrogenatinggas, and the `gas poorer in hydrocarbonsis mixed with the remaining hydrocarbon-rich gas to form thecaloriic'gas. l

In this process the'treatmeiit'of the oil containing the more yreactive and less reactive constituents, and lthe hydrogenation of the less reactive'constituents, 'are carried out in separate tluidised beds to which hydrogenating Vgas is separately `supplied and fromy which the Vgases produced vare separately withdrawn. Thus, the hydrogenation conditions are readily controllable'to suit'the requirements of the ditlerent constituents. VFor example, the fless reactive constituents Amay be hydrogenated under a higher pressure than that used for hydrogenatingthe more reactive constituents. The -use of the gas richer lin ,h5/dio.' carbons for producing the hydrogenating gas enables less steam to be used lthan would Abe necessary if the gas poorer in hydrocarbons vwere used.

The following examples illustrate the invention, the processes described in these examples being carried out with the apparatus shown diagrammatically in FIGS. l and 2 of the accompanying drawings.

Example 1 This is an example `of the process for the production of a hydrocarbon-containing gas suitable as a heating gas, such as town gas, in accordance with the invention, and is carried out in the apparatus shown in FIG. l.

in this process a heavy fuel oilhaving la viscosity of 3000 seconds Redwood (No. 1) is treated in a uidised bed Within a vessel Eil to hydrogenate the more readily reactive constituents at 750 C., and the tar is recovered from the gases produced and hydrogenated at 960 C. in a tluidised bed Within a vessel 11. rlie fluidised beds are composed of coke particles having a 'grain size of 32-72 mesh B.S.S. The hydrogenation in both beds is carried out at 50 atmospheres pressure.

The vessels it) and 11 are associated with means hereinbefore described for dealing with an oil containing constituents that decompose to produce solid carbonaceons material at the temperatures used. Thus, a standpipe 13 opens at its upper end into the iluidised bed in the vessel 1t), and communicates through a passage 14 at its lower end with the lower end of an ascending pipe or upriser 15, through which hydrogenating gas is passed from a line 16 into the vessel 16 so as to maintain the solid particles in the fluidised state. VThe luidised material from the vessel 1G descends into the standpipe 13, in

which the material is kept iiuidised by hydrogenating gas introduced from a line 17. Owing to the hydrostatic pressure due to the height of the uidised material above the level of the passage 14, a Small amount of this material passes into the upriser 15 where it is carried along in suspension in the ascending gas stream, the temperature of the material being substantially the same as that of the material in the vessel 10. The oil is injected at 18 into the upriser 15 so that the bulk of the atomised oil is vaporised and solid carbonaceous decomposition products are carried along in suspension with the suspended particles from the standpipe 13 into the vessel 10. The oil is thus rapidly mixed with the hydrogenating gas and vaporised by the sensible heat of the suspended coke particles and of the gas, and this favours hydrogenation of a high proportion of the oil. The tar, which is to be hydrogeuated in the vessel 11, is similarly injected at 19 into the lower end of an upriser 20 together with solid particles derived from a passage 21 communicating with the lower end of a wide standpipe 22, which communicates at its upper end through a passage 23 with the iluidised bed in vessel 11. Hydrogenating gas is passed through the standpipe 22 to maintain the material therein iluidised, and also to hydrogenate solid carbonaceous decomposition products admixed with the coke particles derived from the vessel 11 and also from the Vessel 10 through a passage 24 communicating with the wide standpipe 22. The diameter of the standpipe 22 must be large enough to give the particles a residence time therein adequate for hydrogenation of the said decomposition products, and normally this diameter should not be less than half the diameter of the fluidised bed in vessel 11. A small passage 25 connects the spaces above the tluidised beds in the vessel and standpipe 22 for the purpose of pressure equalisation.

The greater part of the hydrogenation of the more reactive constituents of the oil occurs in the vessel 10, and completion of the reactions is brought about by passing the gases from the top of the vessel 10 into an empty vessel 26. The methane-containing gas from vessel 26 is then passed through a cooler 27, in which tar is condensed, and a second cooler 2S in which benzole is condensed. Then hydrogen sulphide is removed in known manner in a washer 29, for example, by washing with ethanolamine. The tar from the cooler 27 is introduced at 19 for hydrogenation in the vessel 11.

A part of the hydrocarbon-containing gas from the washer 29 isftapped oi at 30 for treatment to form the hydrogenating gas as described below. Since the gas produced in the Vessels 10 and 26 is richer in hydrocarbons than the gas derived from the hydrogenations in the vessels 11 and 22, the former gas is utilised for producing the hydrogenating gas. The gas from the vessels 11 and 22 are passed tirst through a cooler 31 to remove a tar, which in this case consists mainly of crude naphthalene which can be purified to yield a marketable product. Benzole is recovered in a second cooler 32 and hydrogen sulphide is removed in a Washer 33. The gas from the washer 33 is mixed at 34 with the portion of the gas from the washer 29, which is not used for producing the hydrogenating gas. The mixed gas in the line 35 is diluted with nitrogen (obtained during'the production of the oxygen referred to below) introduced from the line 36 in a proportion suitable to produce'a town gas of appropriate caloric value and density.

The hydrocarbon-rich gas tapped olic at 30 for producing the hydrogenating gas is passed by a blower 37 through a Vessel 38, in which organic sulphur compounds are removed in known manner, for example, by means of alkaline iron oxide at 220 C. Steam and oxygen are then admixed with the purified gas at 39 and 40, respectively, and the gaseous mixture is passed into vessel 41 in which the gaseous hydrocarbons are decomposed in known manner by means of a nickel catalyst at 900 C. into hydrogen and carbon monoxide. The carbon monoxide is then converted in known manner by reaction with the excess of steam in the gas in a vessel 42, and the carbon dioxide is removed from the gas in known manner in a vessel 43. The resulting hydrogenating gas is then preheated to S50-400 C. in a preheater 44 before being supplied to the hydrogenation vessels 10 and 11 and the standpipes 13 and 22.

In carrying out the process by way of example the temperature of the fluidised bed in the vessel 10 is maintained at 750 C. by adjusting the temperature of the hydrogenating gas admixed with the oil at 18 to, say, S90-400 C. The temperature of the bed in the vessel 11 is maintained at 900 C. by adjusting the temperature of the hydrogenating gas to S40-350 C.

InV unit time 37,625 cubic feet of hydrogenating gas are supplied to the vessel 10 per 100 gallons of oil. The compositions of the hydrogenating gas and of the resulting methane-rich gas, having a caloriiic value of 676 B.t.u. per cubic foot, are as follows:

183 pounds of tar are recovered from the vessel 27 and 90 pounds of benzole from the vessel 28. Calculation showed that about 4l pounds of solid carbonacecus products were deposited on the coke particles, most of which products would ow into the standpipe 22 to become hydrogenated.

The 183 pounds of tar so recovered are passed for hydrogenation into the vessel 11. 14,570 cubic feet of the hydrogenating gas are supplied to the vessel 11,` and 3660 cubic feet to the standpipe 22 for the hydrogenation of solid carbonaceous products. The mixed gases derived from the vessel 11 and standpipe 22 have the composition Percent by volume co2 0.1 co 8.4 H2 57.3 cnf4 34.2

Percent by Volume C02 0.2 CO 6.8 H2 46.9 CH4 28.6

924 pounds of steam and 5883 cubic feet of oxygen are introduced at 39 and 40, respectively, for the decomposition of the gaseous hydrocarbons.

7 Example 2 This example illustrates a ptocess for the production of a hydrogen-rich gas in accordance with the invention, and the process is described -with 4reference to FIG. 2.

Within a vessel 50 three iluiiised beds S1, 52 and 53 of coke particles of 32-75 mesh 135,8e are maintained by an upward current of hydrogenating gas. Into the middle bed 52 is introduced Kuwait crude petroleum oil the more reactive constituents of which are hydrogenated in the bed at about 800 C. A light petroleum distillate is hydrogenated in the uppermost bed 51 at about 700 C. Tar from the beds 51 and 52, is hydrogenated at about 900 C. in the lowerrnost bed 53,. The hydrogenations are carried out at 30 atmospheres pressure.

The hydrocarbon-containing gas from the top of the vessel S is passed through a line S4 into a cooler `55, in which the tar is condensed, and then supplied to the bed 53. Benzole and hydrogen sulphide are removed 4from the gas in a cooler 56 and a washer 57 as described in Example 1. The gas -is then passed through a vessel 58 for the removal of organic sulphur compounds. Steam under high pressure is mixed with the purified gas at 59,

and the gaseous mixture is treated in a vessel.60 to decomposethe gaseous hydrocarbons with the steam to form hydrogen and carbon monoxide at 900 C. over a nickel catalyst. The tubes, represented diagrammatically at 61, which contain the Catalyst are 'heated by a .Small ,Supply of the methane-containing gas tapped oif at 62. Before entering the catalyst tubes 61, the gaseous mixture is preheated to 700 C. in a preheater 63 by heat exchange with the hot gases leaving the catalyst tubes, and is then expanded in a turbine 64 to 5 atmospheres.

The hot'gases from the decomposition pass from the preheater 63 into a vessel 65, in which carbon monoxide is converted by reaction with excess of steam in the gas by means of an iron-chromium catalyst at '500 C. into hydrogen. The carbon dioxide so formed is removed in known manner in a vessel 66, and the gas is cooled to atmospheric temperature in a cooler 67. A part of the hydrogen-rich gas so produced is withdrawn as product gas at 68. Another part of the hydrogen-rich gas is passed through a line 69 to a compressor '70, which compresses the gas to 30 atmospheres. The compressed gas is preheated at 400 C. in a preheater 71, and vthen used as the hydrogenating gas.

In order to start the process the plant is iirst lled with hydrogenating gas at 30 atmospheres pressure. The vessel 50 is then warmed by passing through lit hydrogenating gas preheated in 71 to 40G-500 C., the gas being introduced at the bottom of the vessel through a valve 72, a valve 73 in a line 74 being closed. The coke particles, which are to form the iluidised beds, are introduced into the hydrogenating gas at 75. When the vessel 50 is almost full of coke particles, the latter are caused to form the three uidised beds ,by withdrawing surplus particles through lan overflow pipe 76, which determines the upper level of the bed 53, the Vupper levels of the beds 51 and 52 being determined by overllow pipes 77 and 78. A small amount of air for combustion is then admitted to the lowermost bed 53, and lthe air is ignited by the preheated coke particles. The supply of hydrogenating gas is then changed by closing Valve 72 and opening valve 73, so that it passesthrough ythe line 7 4 and passes downwardly through coils 79'and 80 in the beds 51 and 52, and is linally discharged at 81 into the space beneath the lowermo'st bed 53." The supply of air is continued until the temperature in the bed 53 approaches 800 C. The oil is then supplied to the bed 52 and the inal working temperature .is reached with the assistance of the exothermic heat of hydrogenation. The air supply is then shut off. i

8 During normal operation lthe hydrogenating gas is preheated to 400 C. in the preheater 71, and is further preheated to 750 C. in passing downwards through the coils 79 and 80 in the beds 51 and 52, which have Percent by volume co '6.9 H2 29.9 CH., 53.2 y 02H6 10.0

3.07 pounds of benzole are recovered from the cooler 56. The hydrogen-rich gas produced amounts to 2160 cubic feet having the composition Percent by volume Co2 t 2.0 Co 4.3 H2 91.0 CH.. 2.7

Of this gas 1160 cubic feet are withdrawn at 68 as the product gas, and the remaining 1000 cubic feet are passesd through the line 69 and used as the hydrogenating gas.

During operation, coke particles are continually withdrawn from the lowermost bed 53 through the pipe 76 and returned to the upper bed 51, so that there is a continual downward movement of the particles through the series of beds. In this way solid carbonaceous products deposited on the coke particles from the oil in the middle and uppermost beds are hydrogenated in the lowermost bed due to the higher temperature and concentration of hydrogen in that bed.

We claim:

A process for the gasification of a hydrocarbon material which is liquid at a temperature within the range from ordinary temperatures to 500 C. and contains aliphatic hydnocarbons, which comprises subjecting the hydrocarbon material to interaction with a Aproportion of hydrogen suflicient to convert substantially' the whole of the aliphatic hydrocarbon into gaseous saturated hydrocarbons by passing the material and a gas comprising the said proportion of hydrogen under a pressure within the range of 20 to 50 atmospheres through a bed of noncatalytic particulate solid maintained in the uidis'ed state by the gas and having a temperature within the range of about 700 C. to 800 C.

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